Auckland's only native frog is vulnerable to predation by rats, cats and mustelids such as stoats, and threatened by habitat loss.

Voluntary help of landowners in the Dome Valley and Warkworth areas has been vital to Auckland Council ecologists' work on the survey. Rayonier Matariki Forests, one of the largest forestry companies in the country, is among them.

"In order for us to protect this species we need to be able to find out more about them," the council's environmental services manager Janis McArdle says. "Property boundaries mean nothing to frogs, so we want to thank the property owners who allowed us access for our survey work."

Many landowners have become very active in helping the frogs. Some are voluntarily protecting stream habitat by retaining native vegetation in a buffer strip along stream edges and some have been fencing to prevent stock access.

Hochstetter's frogs found between Waipu and Moir Hill are genetically different to those in the Waitakere and Hunua ranges.

They are small, up to 48mm, well-camouflaged, nocturnal, and squeak rather than croak.

Anyone finding native frogs can report sightings to the Auckland Council on 09 301 0101 or contact DOC.